Radiating horn



Dec. 14, 1948. J, R RlssER El-AL 2,456,323

` RADIATING HORN y Filed Jan. 3, -1946 ,Mx FIG .I 32\ OI :OI

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' FIGZ 3g 3o 3T I2 s1 3o 38 I Ie Is .U31 r--q el le im; IIIIII II I II I I I I IIITII 2o I I 1- I I -'I I aI I I I I I I 22" -I I I /25'\. I g 23 I II I IIII fm I I )I I I @I I L III I I I u l I Lfd /l 'J I l WH! l I' .l l YI I I l' -I HHH O l I2( 281 3 3 I3 3| INvENToR f .IAcoB R. RIssI; RMoNo J,wI.ooI owsI A W 9M. 29/ 3| ATTORNEY Patented Dec. 14, 15948 QFFIQ 2,456,323 aanre'rrNG iioRN Application January -3, 1946, Serial No. 638,888

d Claims` (Cl. Z50-33.63)

This invention relates tohorn Atype radiating elements for high frequency communioationsystems or to tapering sections of Wave guide trans.- mission lines and more particularly to a horn of which the flare angles may be variable.

In` order to determine the impedance and radiation characteristics of horns or transition por tionsbetween uniform and tapered waveguide transmission lines, it hasheretoiore been necessary to construct many diner-ent horns or transition sections having various angles of flare which has resulted in considerable loss of time, expense and materials.

Itis one of the objects of thepresent inven tion to prevent or minimize such loss by providing a novel type of horn or transition section` in which the are` angle inv at least one is variable. i

It is another object of the invention to provide a variable angle horn or transition section ior use as a precision test apparatus from which the radiation pattern and impedance'characteristicsvmay be determined.

plane For a better' understanding of the invention together with other and furthe-r oba'ects thereof, reference is had to the following description-,- taken in connection with the accompany-ing drawing, in which:

Fig. 1 is a plan View of a variable angle horn radiating element or a wave guidetransition section according to the present invention;

Fig. 2 is a fron-t elevationv-iew oit-he device of Fig. l; and y Fig. 3 is a sectional viewof the same along-the line 3 3 of Fig. 1.

In the drawing, the horn or transition section lo comprises a waveguide portion II of substantially rectangular cross section having top and bottom walls I 2 and I3' and side walls Hl and l5, connecting at 'throat portion I6 with the ared portion Il. Flared portion Il comprises substantially fan-shaped top and bottom plates I8 and i9 connected to or extending from the top and bottom walls l2 and I3, respectively, of wave guide portion II, and lying in substantially the same planes therewith, and movable side plates 2! and 2i flaring away from each other and preferably disposed at substantially equal angles to the planes of the side walls I l and iii, respectively of wave guide portion Il. The fanshapecl top and bottoni plates i8 and -I9 may be separated iny the `flared portion by two spacing members 22 and 23 and in the throat portion It by the supporting side walls Ill and I of wave guide portion Il. In order to keep the wavelength, of the rectangular-guide portion I I, constant in the transverse electrical eld throughout' the narod-portion between movable side plates 2li' and 21, it is important tomaintai-n thertop and bottom walls I2, I3 of wave guide I-I i andthe top and bottom plates I3 and I9 parallel within a tolerance of plus or minus .003. The spacing betweenv the supporting walls lo and i5 is preferably made equal to the dimension of a wave guide to `which the horn is to be attached orl for which daring is desired and the characteristics thereof tested.

rEhe supporting sidewalls Ill and i5 at the throatV end thereof are out back away from the wave guide aperture as at 2d and-325 in the form of a taper so that the edge of each wall isy brought to a knife edge 25'. The movable side plates 2o and 2i arealso cut back as indicated at 26 and 27 and tapered to afkniie edge 2l at the throat end thereof. The respective knife edges 25 and 2l of side walls It and l5 and movable platesf` and 2i, respectively, are positioned very close together-so that the respective knife edges are in close parallel alignment. Preferably, the knifev edges are spaced by not more than about 0.003".

Exactly in line with the inside edges of side walls it and I5 and about. 0.003 from their knife edge 'points are the centers of two circular bores or sockets 28 and 2?,` in the top andbottom pilates I8 and i9... respectively.. Rotatably fitted in the two aligned bores 28 and 2S are substantially cylindrical pivoter knob members Sil and 3i whicht flush with the inside surfaces of the top and `bottom plates I8 and I9. The movable plates 2o and- 2! have Vtheir top and bottom edge surfaces adjacent the knife edge portion, welded,` solder-ed or otherwise secured as at til and- 34 -tothe inside surf-ace of the top and bottompivot members-@3o and 3l with the inside surfaces of movable plates 2o and' 2i in strict alignment with the pivot centersand with the knife edges 2l" bein-g perpendicular to the inside sur-faces of the pivots stand 3l at the centers, thereof. By this arrangement, the movable plates 2B and 2I are adapted to pivot about theV axis through the centers of pivots `3f@ andV 3l while maintaining their close 'proximity to the Aknife edges 2 5" of side walls -ll and i5. Thus lby means yof Vthis prec-isionlrnife Vedge joint, the movable plates 2t and 2j may be rotated to any angle relative to side walls ifi and l5 without chang-ingv the locatie-noi the corners. lt is important that the Vposition of the corners be kept precise because the impedance of the tapered guide is a function of the distance from each knife edge 21 to the apex of the angle formed by the extensions of the movable plates 20 and 2l; the radius must be, therefore, a known factor. The top and bottom edges of the movable plates 29 and 2i are preferably machined perfectly flat in order to insure both freedom of motion between the parallel plates I8 and I9 and constancy of the guide wavelength throughout the horn or transition portion IB.

To facilitate securing the movable plates 20 and 2l in correct position, an arm member 32 having an arcuate slot 33 therein is attached intermediate the length of the outside surface of each movable plate 2li and 2l as at 33. The movable plates 29 and 2i may be pivoted to any desired position by moving the arms 32, each of which may then be secured in place by means of a lock-nut S4 engaging threaded bolt 35 which is secured to an extension 36 of lower plate iS and projects upwardly through slot 33.

Secured to the upper portion; of each pivot knob 3) as by screws 31 is a pointer member 38 preferably having a straight edge disposed radially of the pivot knob 30, the pointers 38 being secured in position with their straight edges in strict alignment with the inside edges of the movable plates 2U and 2l. If Vdesired,`a calibrated scale, in degrees, may be marked on the top surface of plate i8 whereby movement of movable plates 20 and 2l to a certain angular position may be determined by the pointer `member 38. Thus, the position of the pointer member 38 on the protractor scale indicates the angle of each movable member and thereby the angle of flare of the horn relative to side walls I4 and I5 of wave guide portion Il. j 1

In order to find a radiation pattern or impedance characteristics of a horn of a particular geometry, the test horn lil according to the invention is set so that the movable plates 20, 2l are positioned to the angle required. The free endof the wave guide portion H is attached to the wave guide in the system and tests made in a well-known manner. If necessary, the flare angle of the test horn l0 may be changed to vary the characteristics. By this arrangement, it is p-ossible to determine the proper geometry of a horn for any desired system before actually constructing the same. AIn order to measure the impedance characteristics of the corner formed between a uniform wave guide `and a tapered wave guide, the test horn lil as described may be used as a transition section and shorted to produce the known impedance at the corner, i. e., impedances equal to zero, innity and 1X While there has been described what is at present considered the preferred embodiment of the invention,r it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention.

What is claimed is:

1. A horn adapted to have various angles of flare comprising a rectangular wave guide portion having top, bottom and side walls and a flared portion in communication with said wave guide portion at the throat portion of said horn, said flared portion comprising substantially fanshaped parallel top and bottom plates extending from and in the same planes with the top and bottom walls respectively of said wave guide portion and movable side plates having their top and bottom edges in substantially slidable engagement 4 with the inside surfaces of said top and bottom plates, the throat ends of the side Walls of said wave guide portion and of the movable side plates of said flared portion being cut back to substantially form knife edges perpendicular to said top and bottom plates at the inside corners of each of said wave guide side walls and said movable side plates, the knife edge of each movable plate being in very close parallel relation to the knife 'edge of the adjacent-l wave guide side wall, circular bores in both the top and bottom plates having their axes coinciding with the knife edges of said movable plates, pivot members rotatably seated in said bores having their inner surfaces flush with the inner surfaces of said top and bottom plates, the top and bottom edge surfaces of said movable plates adjacent said knife edges thereof being secured to the adjacent inner surfaces of said pivot members whereby each movable plate is rotatable about its knife edge as an axis and whereby the inner surface of each movable plate is adapted to be positioned at any desired angle relative `to the inner surface of the adjacent side wall of said wave guide portion.

2. A horn as claimed in claim 1 wherein a pointer member is secured to the outer portions of each of the pivot members in the top plate, each pointer member havingV a straight edge lying in the plane of the inner surface of the corresponding movable plate and wherein a protractor scale is marked on the upper surface of said top plate whereby the position of said pointer members relative to said scale determines the exact angular position of said movable plates relative to the inner surfaces of the side walls of the wave guide portion.

3. A horn as claimed in claim 1 wherein said horn is adapted to form a transition section between a uniform wave guide and a tapered wave guide.

4. A precision test apparatus for predetermining the radiation patterns and impedance characteristics of radiating horn elements and of transition sections between uniform and tapered wave guide, comprising a horn, including a wave guide portion including side walls and a flared portion in communication therewith, the flared portion of the horn having side plates which are movable, the adjacent ends of said movable plates and of said side walls being brought substantially to knife edges at the inside corners thereof, said adjacent knife edges being in very close parallel relation, and means for rotatably mounting said movable plates so that each of said movable plates is adapted to rotate about its knife edge as an axis.

JACOB R. RISSER. RAYMOND J. WLODKOWSKI.

REFERENCES CITED The following references are of record in the file of this patent: i

UNITED STATES PATENTS Number Name Date 2,206,683 Wolff July 2, 1940 2,402,622` Hansen June 25, 1946 2,408,373 Chu Oct. 1, 1946 OTHER REFERENCES The Sectoral Electromagnetic Horn, I. R. E. Proceedings, vol. 27, No. l, January 1939, pp. 

